A detailed thermodynamic analysis of the activation parameters for the simple hydrolysis of acetic anhydride in an acetonitrile/water cosolvent system is presented. The activation parameters are obtained using regression analyses of the Eyring rate equation under iso-mole fraction and isodielectric conditions. The iso-mole fraction Eyring plots are linear, indicating the activation enthalpy and entropy are both temperature independent under these conditions. However, the isodielectric Eyring plots are non-linear, and the analysis shows both the activation entropy and activation enthalpy are strongly temperature dependent under isodielectric conditions. The thermodynamic analysis is complemented by linear solvent energy analysis and computational studies of possible transition structures, the latter showing that a concerted six-member ring structure with a single water molecule is the likely transition state.

This article presents the derivation of the thermodynamic expressions for the activation free energy and reaction rate constant for cosolvent reaction systems. These expressions account for the factors that are specific to solution-phase reactions, which include isotropic electrostatic effects and close-range solvent−solute interactions. This article discusses the idea that electrostatic effects can be correlated with the isotropic relative permittivity, and solvent−solute interactions can be correlated with the cosolvent mole fraction. This article also shows that this type of thermodynamic analysis is necessary for understanding certain nuances of solution-phase reaction processes not tractable by other types of analyses. K E Y W O R D Sactivation free energy terms, electrostatic effects, Eyring plots, kinetics, solvent-solute interactions Int J Chem Kinet. 2018;50:873-879.

This article presents reaction rate data for the simple hydrolysis of acetic anhydride in the acetonitrile/water and acetone/water cosolvent systems and regression analyses using recently developed thermodynamic rate equations that contain electrostatic and solvent‐solute terms. The isomole fraction plots for these reaction systems are linear, and previous theoretical work has shown that the electrostatic term is negligible for such systems. On the other hand, the reaction rates are dependent upon the cosolvent mole fraction, indicating that the solvent‐solute term, which is modeled empirically, is significant. The results of the analyses provide the foundation for a paradigm shift away from the emphasis on electrostatic effects to more tenable explanations of kinetic behavior in solvent systems.

Statistical process control (SPC) is used in the chemical industry to monitor manufacturing and laboratory processes to ensure quality and compliance with regulatory requirements. Control charts are a key tool used in this monitoring. Industrial job postings desire experience with SPC. Most undergraduates entering the workforce have no exposure, let alone experience, with control charts. The few available literature examples of control charts in undergraduate chemistry education involve methods of instrumental analysis at the junior or senior level of an academic program. Educators may improve the student’s preparation for working in industrial and regulatory environments by incorporating components of SPC early in the curriculum. This work provides an example of how to introduce the concept and use of control charts earlier as part of the Quantitative Analysis Laboratory curriculum. The titration of vinegar to determine the weight percent of acetic acid, using the same sample for all students, serves as a platform for this introduction. Using a provided control chart generated from historical student data, students stated in a written laboratory report if their results were within control. The scored laboratory reports and questions on the written final exam assessed student learning and retention of how to use a control chart. Meeting the learning outcomes for the laboratory exercise required the student to report the correct weight percent of vinegar and state whether their result is within control. The learning outcomes on the written final exam were met when the student answered the questions correctly, stating the given result was out of control and suggesting correct experimental changes. The goal was to see 70% or more students meet the learning outcomes. Assessment showed that a simple titration experiment enables the introduction of how to use control charts during the Quantitative Analysis Laboratory curriculum.

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